License plate scanners have become a fact of life. They’re attached to traffic lights, on police cars — even “repo” staff use them. All those devices have created a torrent of data, raising new concerns about how it’s being stored and analyzed.

Bryce Newell’s laptop is filled with the comings and goings of Seattle residents. The data comes from the city’s license plate scanner, acquired from the police through public disclosure requests. He plugs in a license plate number, uncovering evidence of long-forgotten errands.